DE29804149U1 - Light emitting diode (LED) with an improved structure - Google Patents

Description

Light emitting diode (LED) with improved structure

The invention relates to an LED device with an improved structure, in particular a wavelength-converting fluorescent powder layer applied to the surface or surroundings of the crystal element or crystal grain, whereby an LED generates white or colored light, which avoids the disadvantages of the prior art caused by different materials or manufacturing processes. When the invention uses a violet-luminous crystal plate, the wavelength-converting fluorescent powder applied to its surface is excited and an LED glowing with any color is generated.

The invention relates to an LED with an improved structure which generates white light, so that the LED generating the white light has a more uniform and increased beam angle compared with conventional products and the simple manufacturing process easily meets the requirements of mass production.

The LEDs used in computers, communication devices, or small household appliances usually emit red, yellow, or blue light, and rarely white light. The reason for this is that the manufacturing process for the LED that produces white light is more complicated, and white light is also more difficult to produce. For example, if an LED can produce red, yellow, and blue light together in one LED unit, white light will be produced when they light up at the same time. However, the white light produced is not easy to control, since the red, yellow, or blue LED crystal element each requires a different voltage and

have different currents.

Recently, Japan Asia Chemical Co. launched its product (patent number in Japan: Te Ping 7-99345), see Fig.1. The special feature of this manufacturing process is that a yellow fluorescent powder layer is first applied to the blue-emitting LED crystal element, and then white light is generated by the yellow light. The disadvantage of this process is that the thickness of the fluorescent powder layer is difficult to control, which leads to unevenness of the white light generated. If the fluorescent powder layer is too thick, the light generated is more yellow. If it is too thin or too little, it is blue. Also, if too much fluorescent powder is distributed around the crystal grain, a yellow light ring is generated on the outer ring of the emitted light point when this product is lit up. This makes it difficult to increase the beam angle of the LED.

As a result, in accordance with the above drawbacks, the inventor has developed an LED which emits uniform white light and whose 0 radiation angle is large and which is suitable for mass production (utility model in China: 97238703.X). This means that when the wavelength-converting fluorescent powder is used, which is placed on the luminous path of the luminous crystal element or crystal grain or applied to the surface or the surroundings of the luminous crystal grain, white light or the desired spectrum is generated. Since the LED crystal grain made of GaN material which generates blue or ultraviolet light is a translucent unit, it is illuminated after the 0 current is connected and emits white light generated by superimposed wavelengths in four directions.

The invention relates to an LED with an improved structure which avoids the disadvantage of the prior art in terms of color deviation caused by different materials and manufacturing processes. When this product uses the violet-luminous crystal plate, the wavelength-converting fluorescent powder applied to its surface can be excited and different colors can be generated by the LED.

In the drawing show:

Fig.l the structure of an LED manufactured by Japan Asia Chemical Co. ;

Fig.2 shows a first embodiment of the invention; Fig.3 shows a second embodiment of the invention; Fig.4 shows a third embodiment of the invention; Fig.5 shows a fourth embodiment of the invention; Fig.6 shows a fifth embodiment of the invention; Fig.7 shows a sixth embodiment of the invention;

Fig.8 is an interior view of the seventh embodiment of the invention;

0 Fig.9 is an enlarged partial internal view of the seventh embodiment of the invention;

Fig.10 is an enlarged partial internal view of the eighth embodiment of the invention,

where:
1 glowing crystal grain;

2 first electrode holder; 21 second electrode holder;

3 resin;

4 Fluorescent resin;

0 41 Fluorescent powder layer;

5 plastic;

6 base frames;

7 filter layer.

Fig.2 shows the structure of an LED according to the invention. First, the luminous crystal grain 1 is inserted into the prismatic groove of the first electrode holder 2 and fixed therein. Thereafter, the first resin layer 3 is applied in the prismatic groove, the thickness of the first resin layer 3 being greater than the height of the luminous crystal grain 1. After the first resin layer 3 is dried, the fluorescent resin 4 is applied, the fluorescent resin comprising the wavelength-converting fluorescent powder and the fluorescent resin 4 forms a thin layer. After the fluorescent resin 4 is dried, it is surrounded with the plastic 5 and the lens-shaped unit of the LED is formed.

The advantages: uniform wavelength, large beam angle and low consumption of fluorescent powder. Fig.3 shows the structure of the second embodiment of the invention. First, the luminous crystal grain 1 is inserted into the prismatic groove of the first electrode holder 2 and fixed therein. Then the first resin layer 3 is applied in the prismatic groove, the first resin layer 3 being slightly thicker than the luminous crystal grain 1. After the first resin layer 3 has dried, the fluorescent resin 4 is applied and a filter layer 7 is applied thereon, which filters the undesirable wavelengths and produces uniform wavelength. If the luminous crystal grain 1 used in this embodiment is the ultraviolet luminous crystal grain, the ultraviolet light can easily excite the fluorescent powder because the ultraviolet light has a short wavelength and high energy and thus strongly excites the fluorescent powder. The ultraviolet luminous

Crystal grain is made of GaN material and can produce wavelengths between 360-390 mm, which are equal to ultraviolet light and harmless to the human body. This means that the ultraviolet light stimulates the fluorescent powder provided in the fluorescent resin 4, which can produce any color, thus making it possible to produce LEDs that glow in different colors.

In addition, when the three fluorescent powders of red, green and blue colors are used in a mixed manner, the white-light LED with three wavelengths can be created, which LED can have a filter layer 7 to avoid harmful effects of the ultraviolet radiation on the plastic 5.

Fig.4 shows the third embodiment of the invention. In the assembly, the resin 5 is arranged first. First, the resin is applied halfway. After drying, the fluorescent resin 4 is applied and then the other half is applied with the resin 5. In this embodiment 0 of the invention, the first resin 3 and the resin 5 comprise the same material. The two comprise plastic. The fluorescent resin 4 is arranged on top of the prismatic groove of the first electrode holder 2 and has an arc-shaped structure so that the conversion of the wavelength 5 can be carried out.

In addition, this embodiment has another application. That is, when the fluorescent resin 4 is applied to the surface of a 3mm LED with a yellow fluorescent powder and a 5mm LED 0 is thereby formed, a white light-generating LED is created. Fig.5 shows that the luminous crystal grain 1 is first

a 3mm LED is formed and then a layer of fluorescent resin 4 is applied to its surface and finally an LED with a 5mm diameter is formed from it using the plastic 5.

Fig.6 shows the construction of the fifth embodiment of the invention. Although the dimensions of the surface-mounted embodiment are smaller than those of the lamp-shaped embodiment, it is widely used. First, the luminous crystal grain 1 is inserted into the groove of the base frame 6. Then, the first resin 3 is applied thereon. After drying, the fluorescent resin is applied and finally the resin 5 is formed. This provides a surface-mounted embodiment of the invention.

Fig.7 shows the structure of the sixth embodiment of the invention. First, the luminous crystal grain 1 is inserted into the groove of the base frame 6. Then, the first resin 3 is applied. After drying, the fluorescent resin 4 is applied and then the filter layer 7 is applied instead of the resin 5. After drying, another embodiment of the invention for surface mounting is created.

Fig.8 shows the seventh embodiment of the invention. First, the luminous crystal grain 1 is inserted into the prismatic groove 5 of the first electrode holder 2 and fixed therein, a fluorescent powder layer 41 is applied in the prismatic groove and this fluorescent powder layer 41 covers the surface and the surroundings of the luminous crystal grain 1. Then, a round LED unit is formed by the plastic 5. The fluorescent powder layer 41 is applied as follows: First

the fluorescent powder is mixed with liquid (alcohol or water with a little adhesive liquid) in portions and applied to the luminous crystal grain 1 so that the fluorescent powder is evenly mixed and flowable and adheres to the surface and the surroundings of the luminous crystal grain 1. After the liquid has evaporated and dried, a thin fluorescent powder layer 41 is formed over the luminous crystal grain 1. Advantages of the invention: uniform wavelength, large beam angle, low consumption of fluorescent powder and easy mass production and thus low manufacturing costs.

Fig.10 shows an enlarged view of a prismatic groove of the eighth embodiment of the invention. First, the fluorescent powder is mixed with the liquid in portions (the thickness of the fluorescent powder layer is thinner than in the first embodiment of the invention) and the prismatic groove is completely filled with it and then heated so that the liquid evaporates and the remaining fluorescent powder layer 41 is formed on the inner wall of the prismatic groove and on the surface of the luminous crystal grain 1. This manufacturing method can shorten the process and produce a uniform wavelength. When white light is generated in the LED of the invention, the blue luminous crystal grain can be used as the luminous crystal grain 1. The fluorescent powder layer 3 comprises yellow fluorescent powder (YAG oxide). Instead, the yellow luminous crystal grain can be used together with blue fluorescent powder. However, such excitation of the fluorescent powder with long wavelength in order to convert it into short 0 wavelength leads to poor radiation performance. However, the blue glowing

Crystal grain has significantly higher manufacturing costs than the yellow glowing crystal grain, so a white light LED is only economical for display and not for illumination. It is better to choose the ultraviolet glowing crystal grain to generate ultraviolet light, whereby the ultraviolet light excites the fluorescent powder on the surface or surroundings and light of the wavelength predetermined by the fluorescent powder is emitted. With different colored fluorescent powders, the desired color of the light can be determined. If white light with three wavelengths is desired, this can be produced by mixing red, blue and green color. The ultraviolet light can easily and strongly excite the fluorescent powder because its wavelength is short and its energy is large.

The ultraviolet luminous crystal grain can be easily manufactured from the GaN material and produces wavelengths between 360-390mm, which are harmless to the human body, like ultraviolet light. The structure of the white light LED manufactured by Jan Asia Chemical Co. is shown in Fig.1. Mainly, the prismatic groove is completely filled with the fluorescent resin 4. This causes unevenness in wavelength. In the invention, the fluorescent powder is directly applied to the surface and the surroundings of the luminous crystal grain, so that the wavelength of the radiation generated by the crystal grain is uniform and the embodiments of the invention are well suited for mass production.

Claims (6)

Expectations 1. LED device which has an electrode holder (2), wherein this electrode holder (2) has a luminous crystal element (1) in its prismatic groove and a first resin layer (3) is applied in its prismatic groove, wherein the thickness of the first resin layer (3) is not less than the height of the luminous crystal element (1); and wherein fluorescent resin (4) is applied to the first resin layer (3) after drying, wherein the fluorescent resin (4) has the wavelength-converting fluorescent powder; and wherein the cured fluorescent resin (4) is surrounded by the plastic (5) to form a convex lens-shaped LED unit. 2. LED device according to claim 1, characterized in that a layer of the wavelength-converting fluorescent resin (4) is applied to a 3 mm LED and an LED unit with a diameter of more than 5 mm is formed from the plastic (5). 3. LED device which has a base frame (6), wherein the base frame (6) has a groove and a luminous crystal element (1) is inserted in the groove, on which the first resin layer (3) is applied, wherein the fluorescent resin (4) is applied to the cured first resin layer (3); wherein the fluorescent resin (4) has wavelength-converting fluorescent powder; and wherein the cured fluorescent resin (4) is surrounded by the plastic (5) to form a surface-mount LED unit. 4. LED device according to claim 1, characterized in that the electrode holder (2) in its prismatic groove the
luminous crystal element (1); wherein the luminous
Crystal element (1) on its surface and in its
Environment with a wavelength converting
Fluorescent powder layer (41) and with the Plastic (5) forms an LED unit; wherein the
The light emitted by the luminous crystal element (1) is in contact with the light applied to its surface and surroundings. Fluorescent powder layer (41) emitting light with
predetermined wavelength. 5. LED device according to claim 1 and 3, characterized
characterized in that the luminous crystal element (1) is a
ultraviolet luminescent crystal element and that the Fluorescent powder in the fluorescent resin (4) to form an LED unit of any color having the corresponding color. 6. LED device according to claim 1 and 3, characterized
characterized in that a filter layer (7) preventing harmful effects of ultraviolet radiation on the plastic (5) is applied to the surface of the fluorescent resin (4).